Although this Salzburg housing development was only finished in 1998, by the summer of 2002 the first 40 of the 117 balconies on the “Erzbischof Karl Berg Estate” had to be refurbished. As effective waterproofing had not been included in the design, water had been able to seep through the joints between the ceramic tiles and into the unprotected balcony slab and the masonry. The result was spalling, plus black stains and damp patches in the apartments.
An unprotected balcony floor slab is particularly vulnerable to damage because it is exposed to severe climatic fluctuations. In the past the properties of concrete have often been overestimated with long-term, reliable waterproofing omitted from balconies. Damage caused by moisture, spalling of the balcony slab concrete due to the effects of water and corrosion of the reinforcement are therefore among the most frequent patterns of damage. Special attention must be given to avoiding thermal bridges. A cantilevering concrete slab, for example, acts as a thermal bridge and can lead to considerable heat losses when the thermal break between the internal and external concrete components is not successful. In such instances there is then the risk of damage in the interior due to, for example, mould growth.
Reliable balcony waterproofing is child’s play with a fleece-reinforced liquid-applied resin. The material moulds to the shape of the underlying construction and is quickly and reliably laid without the need for any naked flames. In order to minimise disruption to occupants, the contractor opted for the solvent-free and hence odourless KEMPEROL 2K-PUR. The work was to be carried out while the occupants were still using their apartments. Although we were working directly in front of the living rooms, nobody complained about any unpleasant smells. To be able to apply a skirting of waterproofing material along the junction with the wall at the back of the balcony, the skirting of ceramic tiles was first removed. Once the substrate was clean and dry, KEMPERTEC EP-Primer was applied with a brush. The primer increases the bond for the subsequent fleece-reinforced KEMPEROL 2K-PUR Waterproofing System, which adheres to the substrate over the entire area. It is therefore impossible for water to seep underneath the waterproofing. And as the material is permanently resilient, the different performance characteristics of concrete, masonry and metals do not lead to any cracking or failures.
Other reasons for selecting the waterproofing system KEMPEROL 2K-PUR were its minimal thickness of just a few millimetres and the fact that it can be laid on virtually all types of substrate. Following thorough investigations, it was decided that it would be unnecessary to remove the ceramic tile finishes in this case – an expensive undertaking. Once cured, the waterproofing was covered with a new layer of ceramic tiles or a hardwearing coating with chippings in accordance with individual occupants’ requirements.